1. Field of the Invention
The present invention relates to a keytop in a keyboard used in a personal computer, a word processor or the like and/or of a key switch used in an IC electronic dictionary, an electronic desk or pocket calculator or the like.
2. Description of the Related Art
As is well known, there have been provided many key switches corresponding to a predetermined key arrangement in a keyboard used in a personal computer, a word processor or the like, and on the top or upper surface of a keytop (keybutton) of each of the key switches is put or applied a letter, a character, a numeral, a word, a symbol, a sign, a figure, a pattern or the like, or any combination thereof each indicating a function of each key switch. A letter, a character, a numeral, a word, a symbol, a sign, a figure, a pattern or the like, or any combination thereof applied on the top surface of each keytop is abraded by repetitively touching it with the tip of a finger so that it becomes blurry or it disappears. For that reason, there has been proposed a keytop in which a letter, a character, a numeral, a word, a symbol, a sign, a figure, a pattern or the like, or any combination thereof applied on the top surface thereof has been coated with a hard resin layer to improve the resistance to abrasion thereof. Here, in the specification, a term “mark” will be used as a generic term for a letter, a character, a numeral, a word, a symbol, a sign, a figure, a pattern or the like, or any combination thereof applied on the upper surface of each keytop.
For example, there has been disclosed in Japanese Unexamined Patent Application Publication No. 59-060824 that was published on Apr. 6, 1984, a keytop on the top surface of which is applied a mark indicating the function of the corresponding key switch and having a transparent synthetic resin applied on the top surface of the keytop including the mark to form a protection layer against abrasion. There has been also disclosed in Japanese Unexamined Patent Application Publication No. 59-171414 that was published on Sep. 27, 1984, a keytop on the top surface of which is applied a mark indicating the function of the corresponding key switch and having a transparent radiation-setting resin applied on the top surface of the keytop including the mark to form a protection layer against abrasion. There has been also disclosed in Japanese Unexamined Patent Application Publication No. 61-008390 that was published on Jan. 16, 1986, a keytop on the top surface of which is printed a mark indicating the function of the corresponding key switch and having a transparent paint applied on the top surface of the keytop including the mark to form a protection layer against abrasion. There has been also disclosed in Japanese Unexamined Patent Application Publication No. 62-237618 that was published on Oct. 17, 1987, a keytop on the top surface of which is printed a mark indicating the function of the corresponding key switch and having a protection layer of an ultraviolet-setting resin formed on the top surface of the keytop including the mark by a tampo printing (also called tampon printing). There has been also disclosed in Japanese Examined Utility Model Application Publication No. 07-024748 that was published on Jun. 5, 1995, a keytop on the top surface of which is printed a mark indicating the function of the corresponding key switch and having a protection film of a transparent or semitransparent hard type ink formed on only the mark portion of the top surface of the keytop by a pad printing (the same printing method as that of the tampo printing).
There will be described in detail with reference to FIGS. 3 and 4 one example of the prior art keytop having the same construction as that of the keytop disclosed in the aforesaid Japanese Examined Utility Model Application Publication No. 07-024748. FIG. 3 is a plan view of the keytop, and FIG. 4 is an enlarged sectional view taken along the line 4—4 in FIG. 3 and looking in the direction indicated by the arrows. A keytop body 11 having a generally square shape in plan is made of a synthetic resin, for example, an ABS (acrylonitrile butadiene styrene) resin. On the top or upper surface of the keytop body 11 are printed two marks (two letters one being an English letter and the other being a Japanese letter, in this example) 12 each indicating the function of the corresponding key switch that is adapted to operate by the keytop, and further, a resin coating 13 is applied on only a portion of the upper surface on which each mark 12 has been printed so that the marks 12 are coated with the resin. Thus, the keytop is formed.
The marks 12 are printed on the upper surface of the keytop body 11 by a silk printing, a tampo printing, or the like. In addition, the resin coatings 13 covering only the portions of the marks 12 are carried out by use of a hard resin such as an ultraviolet-setting (UV-setting) resin or the like, in this example. Such resin coatings 13 can be applied on only the portions of the marks 12 by use of, for example, a tampo printing, as described in the above-mentioned Japanese Examined Utility Model Application Publication No. 07-024748.
There have been proposed keytops each having its keytop body 11 on the overall upper surface of which is formed a coating of a hard resin protecting the marks 12 from being abraded besides that the hard resin coating is applied on only the portions of the marks 12 as the example shown in the figure. In case the resin coating is applied on the overall upper surface of the keytop body 11, it is formed thereon not by use of a tampo printing, but by application of a hard resin solution on the overall upper surface of the keytop body by use of, for example, a spray gun.
As discussed above, in the prior art, the marks 12 each indicating the function of the corresponding key switch have been coated with a transparent or semitransparent hard resin to form a protection layer against abrasion so that the durability (the resistance to abrasion) of the keytop has been increased.
However, in the prior art keytop constituted as discussed above, both the keytop body 11 made of a synthetic resin and the resin coating 13 formed by use of a hard resin such as an ultraviolet-setting resin or the like are hard, and hence an operator's feeling or tactile impression when the operator touches the keytop in operation becomes hard, which results in a disadvantage that it could not be said that the feeling on operation of the keytop is comfortable. In addition, since the keytop is constituted by a hard resin, the tip of a finger is comparatively easy to slip thereon and there leaves a room for improvement in operativity or maneuverability thereof.
Moreover, as shown in FIGS. 3 and 4, in case the resin coating 13 is partly applied on only a portion of the upper surface of the keytop body on which each mark 12 has been printed, a line of the contour of the resin coating 13 is visually identified (caught by eyes), and there is a disadvantage that a grade or quality in the external appearance (high-grade impression) of the keytop is lost.